The present invention relates to a chain of elastic bands, comprising a multiplicity of elastic bands.
It is known from U.S. Pat. No. 4,060,015 to produce elastic bands from a long narrow strip of rubber rolled up on a roll. In a first station a slit which extends in the longitudinal direction of the strip is punched in the strip and in a second station elastic bands are cut off from the strip by means of a further punching device, which cuts through the strip between two longitudinal slits. A handling installation with movable fingers for spreading apart the elastic band cut off by the second station is arranged downstream of the second punching station.
An installation of this type, as described in U.S. Pat. No. 4,060,015, can be located directly upstream of a packing installation, the fingers then supplying the spread-open elastic band directly to the packing installation. This implies that a relatively complex punching device, which is susceptible to malfunction and often is expensive, for punching elastic bands from the strip has to be arranged by every packing installation. It is also possible to produce the elastic bands beforehand and to supply these from a storage container to a packing installation. In this case, however, the packing installation must be provided with a complex set of fingers, gripper elements, etc., in order to take the elastic bands, which are stored in random fashion, from the storage container and then to spread these open and stretch them around one or more desired articles.
U.S. Pat. No. 3,572,396 discloses a chain of elastic bands which consists of a rubber, oval tube which has incisions in the transverse direction at regular intervals in such a way that only two connections remain in the longitudinal direction. The tube is essentially oval with two parallel flat sides which are connected to one another by curved end sections. A chain of elastic bands of this type is produced by feeding a tube of elastic material to a cutting block, pressing the tube flat on said block and then cutting into the tube down to the block using a blade. However, a chain of elastic bands of this type has the disadvantage that when cutting into the tube the parts thereof which are pressed onto one another easily stick together, as a result of which the elastic bands no longer fall open by themselves. This leads, in turn, to malfunctions when a chain of elastic bands of this type is used in an automatic packing installation as a pre-determined fixed positioning of elastic bands is no longer guaranteed. According to said U.S. Pat. No. 3,572,396, the feed to a bundling installation takes place from a magazine in which the tubular chain of elastic bands is stored vertically. Each time, the lowermost elastic band is rotated through 90.degree., after which it can be gripped by fingers and pulled from the tube. This rotation through 90.degree. and subsequent gripping is highly susceptible to malfunctions if the elastic band is not correctly positioned. This is the case, for example, when sticking together has occurred or when the tube has not been cut through to an adequate extent, as a result of which the tilting movement of the lowermost elastic band is impeded. A further malfunction factor is that not only the lowermost elastic band but also the lowermost two or even more elastic bands can be rotated through 90.degree. and then would be fed to the fingers simultaneously.
Furthermore, German Offenlegungsschrift 2 223 759 discloses annular packaging elastic bands made of rubber, which elastic bands are connected to one another in chain form and are separable from one another. As in the case of the abovementioned U.S. Pat. No. 3,572,396, here too the chain of elastic bands is produced from a rubber hose which is cut into in the transverse direction and at intervals. The problem of elastic bands sticking together again arises in this case as well. In order to form the chain of elastic bands, the hose is pressed flat and then cut through except for a small section. In this case, the section which is not cut through provides a connection to an adjoining elastic band. The section which is not cut through is always located at an opposing side to the previous one, so that a chain of elastic bands which is, as it were, harmonica-shaped is formed after cutting into the rubber tube. Said harmonica-like chain of elastic bands can be converted into a long chain of successive elastic bands by completely unfolding the harmonica-like chain. Said drawn out chain of elastic bands can then be wound onto a roll, after which the elastic bands can be torn off from the roll one-by-one for use. Stresses are introduced into the chain of elastic bands both when unfolding the harmonica-like chain and during the subsequent rolling up onto the roll, as a result of which the elastic bands will lose elasticity during storage of the chain on a roll. When the chain of elastic bands is rolled up onto the roll, the elastic bands are pulled closed, so that the fingers of an automatic bundling installation would not be able to be inserted into the elastic bands, or would be able to be inserted only with difficulty and in an unreliable manner. The chain of elastic bands disclosed in German Offenlegungsschrift 2 223 759 is therefore not suitable for use for automatic packing installations.
Furthermore, many installations are disclosed in the prior art with which elastic bands are produced by cutting these off from a hose and then supplying them to a packing installation. In order to be able to operate without malfunctions, it is necessary that an open elastic band is supplied to the spreader mechanism. However, the problem with this simple cutting method, which is necessarily used, is that the elastic bands stick together and consequently do not fall open.